This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Systemic delivery of HDAd by injection into a peripheral vein has been widely employed for liver-directed gene transfer for the purpose of gene therapy due to the method's simplicity and noninvasiveness. However, in order to achieve efficient hepatocyte transduction, high doses of vector are required which unfortunately result in severe acute toxicity. Attempts to circumvent this obstacle have been made by direct vector injection into the portal vein of the liver. However, the results, in terms of toxicity and hepatocyte transduction efficiency, were no different than following peripheral vein injection. The objective of this project is to determine the feasibility of delivering helper-dependent adenoviral vectors exclusively to the liver for hepatocyte gene transfer by first isolating the liver circulation prior to delivery of the vector via the portal vein. We hypothesize that this strategy will result in high efficiency hepatocyte transduction using significantly lower vector doses and thus reduce, if not eliminate, acute toxicity. Furthermore, the ability to control the liver circulation may permit efficient transduction in the presence of preexisting neutralizing anti-Ad antibodies, important for later vector readministration, as well as prevent systemic dissemination of the vector, which would further improve safety.